BAT

Description
The BAT gives an overview of services within a group. The services can also br located beyond the borders of their own network.
Through the BAT a provider can build a channel list from the available channels, even outside their own transponders. Identification of a Bouquet is done by the Bouquet ID. An overview of these codes can be found in the ETR_162 or online
BAT can be found at PID 17,same as the SDT. Identification of the BAT tables is done by using different table_id's. BAT tables use table id 0x4A.
Features
  • If present, all sections of the BAT should be broadcasted at least each 10 seconds.
  • A service can exist in multiple bouquets
  • Descriptors
    The following descriptors may appear in the BAT :
  • service_list_descriptor
  • stuffing_descriptor
  • bouquet_name_descriptor
  • scountry_availability_descriptor
  • linkage_descriptor
  • CA_identifier_descriptor
  • multilingual_bouquet_name_descriptor
  • private_data_specifier_descriptor
  • default_authority_descriptor
  • extension_descriptor
  • user_defined_descriptor

  • name bits description
    BAT
    Table ID 8 Indicates to which table this section belongs, in this case BAT (0x4A)
    section_syntax_indicator 1 Indicates whether a sub-table structure including CRC check is used.
    reserved_for_future_use 1 always binary value '0'
    Reserved 2 always binary value '11'
    Section length 12 The length of the section in bytes. This length starts immediately after this field and includes the CRC. The maximum length is 1021 so the section is up to 1024 bytes long.
    Bouquet_id 16 Indicates the Bouquet ID
    reserved 2 always binary value '11'
    version_number 5 Value between 0 to 31.
    A higher value indicates that the information has changed.
    current_next_indicator 1 This is to indicate whether a section is 'valid now' or 'valid in future'
    section_number 8 Value between 0x00 - 0xFF. Used to indicate the sections of a table. Up to 256 sections.
    last_section_number 8 The number of the last section, so the receiver know when the table is completely received.
    reserved for future use 4 always binary value '1111'
    bouquet descriptors length 12 The length of the Bouquet Descriptors loop
    Bouquet descriptor loop
    reserved for future use 4 always binary value '1111'
    transport stream loop length 12 The length of the transport stream loop
    transport stream id 16 This 16 bit field indicates the transport stream ID for identification of the transport stream in the network.
    original network id 16 This 16 bit field shows the original network id.
    reserved for future use 4 always binary value '1111'
    transport descriptors length 12 Indicates the total length of the transport descriptors loop
    transport descriptors loop
    CRC_32 32 Cyclic redundancy check